Plate developer



Jn. l1, 1949. .1. T." CAMPBELL Jan, 11, 1949.

J. T. CAMPBELL PLATE DEVELOPER 2 Sheets-Sheet 2 Fned oct. 31, 1945 (isfPatented Jan. 11, 1949 UNITED STATES PATENT OFFICE 3 Claims.

This invention relates to a developing tank, and more particularly to aphotographic plate developing mechanism characterized by means formaintaining a uniform tank temperature.

Heretofore, in plate developing apparatus and in the devel-opment ofsensitized metal printing plates, considerable difficulty has beenexperienced in obtaining uniformity of quality. This has been due tochanging temperature conditions which heretofore have been compensatedfor by variations in the developing time.

It is the principal object of this invention to provide refrigeratingand heating units in conjunction with the developing tank t-o maintain aclose differential in temperature in all seasons and in all weather.Thus a constant developing time can -be established which is not subjectto the varying Weather conditions and temperature, which heretoforevaried the developing .time and required guessing as to the properdeveloping time.

As the developing time varies with changes of temperature and humiditythe workman was continually confused and uncertain as to the exactprocedure to follow in this important operation. The present inventionis therefore adapted to provide for a substantially uniform tanktemperature with a resultant constant developing time eliminating allguesswork.

It is the object of this invention to provide a substantially verticalinsulated plate developing tank, together with heating and cooling meanstherefor, to regulate the tank temperature.

It is the object of this invention to provide regulatable thermostat-icmeans in conjunction with said heating and cooling means for maintaininga substantially uniform .tank temperature.

It is the further object of this invention to provide a dual thermostatswitch characterized by separately rotatable temperature regulatingdials for said heating and cooling means, together with a connectinglink between said dials whereby a Xed temperature differential ismaintained therebetween, regardless of their adjustment.

These and other objects will be seen from the following specificationand .claims in conjunction with the appended drawings, of which:

Fig. 1 is a side elevational view of the plate developer.

Fig. 2 is a top plan view thereof rotated 90 degrees counter-clockwise.

Fig. 3 is a front elevational view thereof, and

Fig. fl is an enlarged elevational view of the thermostat control panel,and

Fig. 5 is a diagrammatic View illustrating the switch, its temperatureresponsive elements and the electrical connections for controlling theheating and cooling means.

It will be understood that the above drawings illustrate merely onepreferable embodiment of the invention and that other embodiments arecontemplated within the scope of the claims hereinafter set out.

Referring to the drawings, Fig. l, a motor base I I of hollowconstruction is shown. Hollow tank frame I 2, with removable bottommember I3, has an angularly formed anchor plate I4 welded or otherwisesecured thereto adjacent the lower longitudinal edge thereof. Tank I2 isangularly arranged and supported at the end of base II with thehorizontal portion of anchor plate I4 being secured to the top of saidbase ,by a plurality of spaced screws I5.

Hollow developing tank I6 with steel false bottom I8 is positionedwithin tank frame I2 in spaced relation to its side walls. The upperportion of tank I6 flares outwardly at I9 and is bent down at points 20to t over the front, rear and side walls of frame I2 for supportthereon.

The front portion 2I of tank I6 extends upwardly as shown in thedrawing. The rearward portion of tank I6 has a pair of upwardlyextending spaced ears 22 providing a pivotal support at 23 for the twospaced members 24 which extend rearwardly from pivotal cover 25, withhandle 2E.

Copper cooling coil 2'I is soldered or otherwise secured to the rearwall of tank IB, and is adapted to carry a refrigerant supplied to oneend of said coil from an expansion valve not shown within -box 28carried on the rear wall of frame I2.

A condenser 29 is shown dlagrammatically positioned on base II forsupplying a liquid refrigerant to said expansion valve. Compresser Si]and operating motor 3| are likewise positioned on base II and associatedwith condenser 29 to make a completely operative refrigerating unitsupplying refrigerant to cooling coil 21. The detail and operation ofsaid refrigeration unit, per se, forms no part of the 'present inventionexcept as a unit or element in itsel-f forming a part of the combinationset out herein; and consequently its detail and operation are omittedherein.

Referring to Fig. 1, a heating coil 32 is wound around the lower portionof tank IB and consists of an enclosed electric resistance heating cablecontrolled by a suitable thermostat. Said thermostatis responsive to thesetting of dial 33 on dual thermostat switch 34 shown in Fig. 4 withvits cover I'I removed. Similarly, the refriger- .ating unit 27, 29, 30and 3| is controlled by a suit- 3 able thermostat which is regulated byrotatable dial 35 `on switch 34.

Switch 34, shown enlarged in Fig, 4, is illustrated in Fig. 1 supportedon bracket 36 and having a cover I'I. Referring to Fig. 4, the coolantcontrol dial 33 and heater control dial 35 are calibrated in degrees,and are set relatively to the two indicating arrows 36.

From-Fig. 4 itisseen thatdial.35.is set .at Y(3'7" and dial33iat 65?,whereby whenfthetemperature of the developing uid in tank I6 drops below65, the heater coil 32 will be energized. Similarly, shoul-d thetemperature cf the developing uid rise above 67, the refrigerating unit:f'motorf3l will be energized. It will be seen that preferably atwo-degree diierential is maintainedbetween the heating and coolingunits-.aso thatxthezsituation of both units operating simultaneously isavoided.

Dials 33 and 35 are initially set using a thermometerinthe fluid'Y tankI 6 by rotatably-"adjustlingzinner-dials 3'I\and 38 and tightening'screws 39. Dials 33 and 3-5`may now be rotatably adjusted-andset foranyfdesiredtemperature.

Dials-33 and 35 `may be-adjusted-manuallyby inserting a screwdriverthrough arcorresponding fopen-ingr in' switch cover I"Iy and into 'discrecess '4IJ. Connecting link 4I respectively joins Vdials33 and@SSI-byfscrews Iand-143 wherebysaid dialsare Vsynchronized to `rotate in`unison. Thus ta "Xed -2-degree :or other spacing is constantlymainitained between saidr dials vto guarantee that both "heating`andcooling` unitsiwill not be simultaneously Lenergized. The lrotaryadjustment of dial f35f'effects afsiunultaneous correct andcorres'pon'd- `ingadjustment of dial 33. Figure'- is adiagrammatic -Viewillustrating .the thermostat rv152 lwith contact element 53 forenergizing compressor cperatingelectric motor.'-'3I 'for controlling thecoolingmeansi2l `A secondfthermostatic switch u54 -with 'contact element55 is employed 'for'enerfgizing the -electricresistance-coil 32 'forcontroli 'ling s said heating v element.

Referring to Fig. 11, with'tank [-6 inserted in "frame I2, the space454-thereb-etweenisilledfwith a suitable f insulating material 145 lbefore bottom I3is`secure`d in place. r"IanfkfI6='is=so'1wel1 insulate'dthata neutral temperature Vis maintained a :substantialpa'rtfof lthetimerbetweenthe two 'temperaturesettingsoi dials 33-an`d35.Consecuently, 'most of the time -neither heating nor .cooling 4unit*will `l be energized.

Referring'to'fFig. 1, curved motor r`cover 46 -has 'alange "41 'atyits`upper endwhi'ch is-secure'dV -to .the rear walloftank frame I2 byscrews48. The

loweredgeof'cover 46 has afianged portion 49 lsecured' to base I I -byscrews 50. lSpaced screen Inernbers5l'are'secured totheside Wall-*edgesof cover 46 for completely enclosing ythe operating mechanism of the:plate developing unit, at the same time permitting the free circulationof air therethrough.

Having described my invention, reference should now be had to the claimswhich Vfollow for determining the scope thereof.

I claim:

..1. ATA plate L,developer comp-rising. a ...-base, a re- 'fri'geratingmechanism rsupportedithereon, a hollow rectangular angularly arrangedframe sezcured thereto, a hollow developing tank suspended within saidframe in insulated and spaced Arelation thereto, cooling means securedto the `Wall,oisaidftank and joined ito said refrigerating mechanism,and heating means positioned *around aportionof said tank.

4,2....LLplate developer comprising a base, a re- "frigerating mechanismsupported thereon, a hollow rectangular angularly arranged frame se-=`cured thereto, a hollow developing tank sus- 'pendedf'withinsaidframelin insulated and spaced relation thereto, cooling means secured tothe wall 'of -saidtank-:andjoined to said reirigerating mechanisrmheating'means positioned'around a jportionof rsaid tank, `and athermostat switch carried'bylsaid frame and joined tosaid heating landcooling means-for separately energizing the `'same f atpre determinedtemperatures.

3. -A plate developer comprising a base, arefrigeratingmechanism'supported thereon, a holllow 'rectangular angularly arrangedframe secured' theretda :hollow developing tank suspended EwithinT saidfra-me `in insulated and Yspaced relation-thereto, a cooling-coilsecured to a wall of said'tank and'joine'd'to-said refrigerating mech-"anism, 4van lelectric "resistance Acoil positioned `around -a lportionof said tank, a thermostat switch, a `rotatable temperature calibrateddial on saidswitchfelectrically-joined to said refrigerating mechanism,a rotatable temperature calibrated-dial `on said switch joined to saidresistance "coilyI and a 'synchronizing link interconnecting saiddialswhereby, on rotary-adjustment of one AVtlrieutemperature diiierentialsetting therebetween f is f maintained.

JAMES T. CAMPBELL.

REFERENCES CTED "The following references are of record in the 'file of`vthisjpatent:

UNITED STATES PATENTS Number Name Date f v1,772,834 Hopkins Aug. 12,1930V-1,810,85'7 Thomfpsonet al. 'June 16, 1931 1,958,791 vvKalbfleisch etal. May 15, 1934 n2,149,085 Crago Feb. 28, 1939

